In less than a month, McDonald's has more than doubled the number of its U.S. locations that offer delivery.

CEO Steve Easterbrook told shareholders at a Bernstein investor conference Wednesday that delivery is now available at more than 2,000 locations and that he expects the partnership with UberEats to expand to more than 3,500 locations by the end of June.

"We are encouraged by early results in the U.S. where delivery is resonating well, particularly with our younger customers," Easterbrook said.

In the U.S., 60 percent of delivery orders were placed in the evening or late at night, and arrived, on average, within 30 minutes, he said.

Delivery has become a key priority in fast food, but hiring a fleet of drivers can be a huge undertaking for chains. Companies like Uber, Postmates and DoorDash, among others, can help ease the financial burden on restaurants by acting as a third-party delivery service. The trade-off is the chain doesn't have direct control over the employees making the deliveries.

McDonald's already has well-established delivery services in Asia and the Middle East, where for some restaurants delivery is 40 percent of sales. Last year, the Golden Arches garnered nearly $1 billion in delivery sales globally.